lib/list_debug.c

   1 /*
   2  * Copyright 2006, Red Hat, Inc., Dave Jones
   3  * Released under the General Public License (GPL).
   4  *
   5  * This file contains the linked list validation for DEBUG_LIST.
   6  */
   7
   8 #include <linux/export.h>
   9 #include <linux/list.h>
  10 #include <linux/bug.h>
  11 #include <linux/kernel.h>
  12 #include <linux/rculist.h>
  13
  14 /*
  15  * Check that the data structures for the list manipulations are reasonably
  16  * valid. Failures here indicate memory corruption (and possibly an exploit
  17  * attempt).
  18  */
  19
  20 bool __list_add_valid(struct list_head *new, struct list_head *prev,
  21                       struct list_head *next)
  22 {
  23         if (CHECK_DATA_CORRUPTION(next->prev != prev,
  24                         "list_add corruption. next->prev should be prev (%px), but was %px. (next=%px).\n",
  25                         prev, next->prev, next) ||
  26             CHECK_DATA_CORRUPTION(prev->next != next,
  27                         "list_add corruption. prev->next should be next (%px), but was %px. (prev=%px).\n",
  28                         next, prev->next, prev) ||
  29             CHECK_DATA_CORRUPTION(new == prev || new == next,
  30                         "list_add double add: new=%px, prev=%px, next=%px.\n",
  31                         new, prev, next))
  32                 return false;
  33
  34         return true;
  35 }
  36 EXPORT_SYMBOL(__list_add_valid);
  37
  38 bool __list_del_entry_valid(struct list_head *entry)
  39 {
  40         struct list_head *prev, *next;
  41
  42         prev = entry->prev;
  43         next = entry->next;
  44
  45         if (CHECK_DATA_CORRUPTION(next == LIST_POISON1,
  46                         "list_del corruption, %px->next is LIST_POISON1 (%px)\n",
  47                         entry, LIST_POISON1) ||
  48             CHECK_DATA_CORRUPTION(prev == LIST_POISON2,
  49                         "list_del corruption, %px->prev is LIST_POISON2 (%px)\n",
  50                         entry, LIST_POISON2) ||
  51             CHECK_DATA_CORRUPTION(prev->next != entry,
  52                         "list_del corruption. prev->next should be %px, but was %px\n",
  53                         entry, prev->next) ||
  54             CHECK_DATA_CORRUPTION(next->prev != entry,
  55                         "list_del corruption. next->prev should be %px, but was %px\n",
  56                         entry, next->prev))
  57                 return false;
  58
  59         return true;
  60
  61 }
  62 EXPORT_SYMBOL(__list_del_entry_valid);